Maile T. Phillips of Yale University, and colleagues, used data from Project Tycho to estimate seasonal and long-term typhoid transmission. They characterized seasonal and long-terms trends in typhoid transmission and quantified the relationship between infrastructure investments and declines in transmission rates.
Related Project Tycho Datasets
Background: Investments in water and sanitation systems are believed to have led to the decline in typhoid fever in developed countries, such that most cases now occur in regions lacking adequate clean water and sanitation. Exploring seasonal and long-term patterns in historical typhoid mortality in the United States can offer deeper understanding of disease drivers.
Methods: We fit modified Time-series Susceptible-Infectious-Recovered models to city-level weekly mortality counts to estimate seasonal and long-term typhoid transmission. We examined seasonal transmission separately by city and aggregated by water source. We fit regression models to measure associations between long-term transmission and financial investments in water and sewer systems.
Results: Typhoid transmission peaked in late summer/early fall. Seasonality varied by water source, with the greatest variation occurring in cities with reservoirs. Historical $1 per capita ($25.80 in 2017) investments in construction and operation of water and sewer systems were associated with 8-53% decreases in typhoid transmission, while $1 increases in total value or debt accrued to maintain them were associated with 4-7% decreases.
Conclusion: Our findings aid in the understanding of typhoid transmission dynamics and potential impacts of water and sanitation improvements, and can inform cost-effectiveness analyses of interventions to reduce the typhoid burden.
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